The present invention concerns an automatic focusing device for use in a camera. Automatic operation for cameras has been developed along with introduction of electronic constitutions into cameras in recent years. Particularly, cameras having an automatic focusing device for automatically conducting the focusing operation are very much convenient since photographs can be taken at high quality without so-called "out of focus" even by those persons having no particular technical knowledges and not trained specially, by a simple operation of directing a camera to an object and pushing a release button.
While on the other hand, there has also been made generally to assemble the automatic focusing device into a camera provided or detachably mounted with a zoom lens or a variable focus lens having such a wide variable focal length region that the focal length is variable, for example, from 35 mm to 135 mm by one lens set without exchanging several lenses of different focal lengths. The shortest object distance capable of taking photograph in such a camera (hereinafter simply referred to as "nearest distance") is often set to about 1 m although it is different depending on the lens focal length. That is, it is possible to take photograph over a wide range of 35 mm-135 mm as the focal length and about from 1 m to infinite distance (hereinafter simply referred to as ".infin."), as the object distance.
Further, there is also a lens (camera) capable of macro photographing that can take a photograph even for an object at a distance nearer than the nearest distance (about 1 m) described above without exchanging the lenses, in addition to such a wide photographing range described above.
A distance measuring section is disposed as one of the components of the automatic focusing device for measuring the object distance. Various methods have already been proposed for the distance measurement conducted in the distance measuring section and they can include, for example, a method of recognizing an intended focused position by detecting the defocusing amount on the film surface (the extent for the deviation of the focused position), called as a correlationship method, which uses a charge coupled device, that is, a known solid state image pick-up device (hiereinafter simply referred to as "CCD") as the photoreceiving element for detecting the defocusing amount.
By the way, in a camera having the automatic focusing device incorporated therein and a lens system having the variable power function and the macro function mounted thereto, it is necessary for the judgement as to whether the lens system should be switched to the macro region or not in a case where the focused state can not be obtained even after the lens system has reached the end at the nearest position in the variable power region. That is, some information has to be provided to a camera operator.
However, in a camera comprising a lens system having the foregoing function and the automatic focusing device, since not only the object distance relative to an identical defocusing amount varies but also the errors in the detection section and the calculating section are different depending on the setting state (mm) for the entire focal length of the lens system (mm) upon arriving (stopping) at the nearest end position, it can not be judged as to whether the focused state is obtainable or not by the switching to the macro region only based on the distance measuring data from the distance measuring section. Accordingly, the camera operator can not cope at all with such situation as described above since the inside state of the camera is quite unknown. In view of the above, it has been taken such a conventional means as indicating only the direction where the focusing possibility is present, for example, by as arrow display, although it can not ensure the actual possibility for the focusing (photographing).
However, in the conventional device of this kind, photographing is not always possible since there is no guarantee for attaining the focused state if the lens system is switched to the macro region and there is even a risk of losing a valuable shutter chance while conducting such wasteful switch operations. Even in a case where there is no such risk, operator will be disappointed and feel displeased. Further, there has also been a problem that the time is consumed wastefully since no appropriate countermeasures can be taken.
In the automatic focusing device as described above, in a case where the focusing lens is driven to the end position on the closest side and yet the focused state is not judged, since the movement of the focusing lens is mechanically stopped at the end, overload is continuously exerted undesirably on the driving means such as a motor. In view of the above, it has generally been adapted that a normally open type switch, for example, is disposed at the end position to detect the arrival of the focusing lens when it reaches the end position and closes the normal open type switch, or a rotary encoder or the like is connected with the focus lens to detect the arrival at the end position if the output pulses from the rotary encoder does not change for a predetermined of time, to thereby stop the driving for the focusing lens automatically hereinafter.
However, there is a scattering in the detection output from the focal point detection means and an erroneous information indicating as if an object to be focused were at a position out of the focusing distance should be outputted temporarily even if the object is at the position near the shortest photographing distance or the infinite distance within the photographing distance range. For instance, in a case where the object to be focused is at the position near the shortest photographing distance, the focusing lens is driven and arrives at the closest end position by such a temporal erroneous information as described above, and the focusing lens is no more driven by the end detection. That is, there has been such a drawback that although the focusing object lies within a photographic distance range capable of focal point adjustment, no proper focal point adjustment can be conducted. The same disadvantage as described above may also occur at the end position of the infinite distance in a case where the focal point detection device is constituted so as to stop the driving for the focusing lens in the infinite end position.
For overcoming such disadvantages, Japanese Patent Laid-Open No. Sho 49-204813 discloses an automatic focal point adjusting device in which the driving for the focusing lens is once stopped when the end detection is made and then the final driving mode for the focusing lens is determined depending on the result of comparison between the data for the deviating directions obtained from the focal point detection means at the instance before or after the thereof.
However, in a case where an object to be focused is focusable in the macro region, in a photographing lens having the macro function, if the photographing lens is not situated within the macro region, the driving control to the focusing lens after the end detection is not made at all by the end detection in the conventional example described above. That is, there occurs a disadvantage that no appropriate focal point adjustment can be made will all that the object to be focused is within the photographing distance range capable of adjusting the focal point.
Further, Japanese Patent Laid-Open No. Sho 58-105113 proposes a lens control device in which the end detection for a lens is conducted if there is no change in the signal relevant to the shifting of the lens for a predetermined of time, and a further movement of the lens in the identical direction is inhibited. However, the conventional device of the latter type also provides a similar disadvantage to that in the device described above.
Further, the respective movements of the lens groups in a camera incorporating the automatic focusing device and having the variable power function and the macro function as described above include the movement due to the focus adjusting operation (hereinafter simply referred to as "focusing movement"), and movement due to the setting operation to the focal length and the setting operation to the variable power region or to the macro region (hereinafter simply referred to as the "setting movement"), and some lens group has to move in dual mode. Then, the moving amount for each of the lens groups in the focusing movement and the setting movement is specifically regulated by the shape of the cam diagram (cam groove) defined upon design of the photographing lens.
While on the other hand, as the structure of the camera has been made more and more compact, there is a demand that protruding portions should be decreased as much as possible in a state where the camera is not used. In view of the above, in a case where a variable focus lens of a large projecting amount is used as the photographing lens, it is considered to dispose a containing region for retracting the protruded portion of the photographing lens as well as the variable power region and the macro region to the inside of the camera main body to the above-mentioned cam diagram (cam groove). In this case, these three regions are connected in series by means of one cam groove in one lens group. Accordingly, if the lens group comprises 5-group of photographing lenses, five stripes of cam grooves are present at least for the setting movement. Further, a portion of the five groups, for example, two lens groups conduct the focusing movement and they undergo dual movement, that is, driven by independent driving systems respectively, by which the moving mode of the lens groups is complicated. As a result, it may be considered such a case where the setting movement, for example, of switching the photographing lens from the variable power region to the macro region may cause interference between the adjacent moving frames depending on the way of constituting each of lens groups and can not be conducted smoothly.
While on the other hand, the focusing movement range (region) described above includes a variable power focusing region and a macro focusing region corresponding to the variable power region and the macro region respectively. For instance, expressing by the object distance, the range from .infin. (infinity distance) to 1.2 m is the variable power focusing region and the succeeding range from 1.2 m to 0.5 m corresponds to the macro focusing region. In the variable power region, when the focusing lens group is moved from the .infin. position to the nearest position between the .infin. position and the, nearest position on the optical axis corresponding to the object distance: .infin.-1.2 m, if the moving direction is assumed as positive, since the automatic focusing mechanism is constituted by setting the operation in the variable power focusing region as the standard, the variable power focusing region and the macro focusing region agree with each other. Upon moving in the positive direction also in the macro focusing region, the position on the optical axis corresponding to the object distance 1.2 m corresponds to the .infin. position (hereinafter simply referred to as "MACRO .infin. position"), while the closest position on the optical axis corresponding to the object distance 0.5 m corresponds to the nearest position in view of the automatic focusing mechanism. However, the change of the object distance is continuous from the variable focusing region to the macro focusing region, that is, from .infin. to 0.5 m. Now, assuming that the focusing lens group is at a position on the optical axis corresponding to the object distance 1.2 m and the photographing lens is set to the variable power region, the optical focusing lens group considered to be set at the nearest position in view of the automatic focusing mechanism. However, if the setting to the photographing lens is switched from the variable power region to the macro region while maintaining the position of the focusing lens group as it is (that is, under the state not operating the focusing driving means), the position of the focusing lens group is switched to the closest position corresponding to the object distance 0.5 m in view of the automatic focusing mechanism. That is, although the physical position of the focusing lens group is not varied, switching for the setting of the focusing lens region results in the disagreement for the position of the focusing lens group in view of the automatic focusing mechanism, to thereby bring about a disadvantage in view of the focusing.
Further, the defocusing amount of the actual focused position of the object relative to an intended focused position is different between the variable power focusing region and macro focusing region, and the automatic focusing control in the variable power focusing region can not be applied as it is to the automatic focusing control in the macro focusing region. This constitutes one of the factors inhibiting the attainment of the automatic focusing in the case of using the photographing lenses of this kind.
By the way, in a photographing lens in which the variable range of the focal length in the variable power region is, for example, from 135 mm as the longest focal length (hereinafter referred to as "TELE side") to 35 mm as the shortest focal length (hereafter referred to as "WIDE side"), a predetermined focal length in the macro region is 80 mm and cam grooves determining the movement (moving amount) for each of the lens groups in these regions are in continuous from the TELE side to the macro region, the each of the lens groups moves upon switching the photographing lens in the order of 80 mm of the macro region .fwdarw.135 mm of the variable power region. Then. it is generally adapted such that the driving for each of the lens groups is stopped when reaching 135 mm (TELE side end) of the variable power region. However, the distance measuring data from the distance measuring section contain a scattering even for an identical object distance and, since the focal depth is shallow particularly on the TELE side, it may cause erroneous information by such scattering, for example, that the distance measuring data for an object situated at the object distance 1.2 m corresponding to the nearest side end is indicated as 1.3 m or as 1.0 m on the side of the macro focusing region corresponding to the macro region. Then, if the distance measuring data as the erroneous information is 1.0 m, the control section in the camera judges it as macro photographing possible to display the macro photographing possible direction as described above and maintain this state till the operator actuates the changing switch. That is, there is a problem that the operator is confused upon the demand of returning again to the macro region even after he has once switched from the macro region to the variable power region.
While on the other hand, although each of the lens groups is moved accompanying the switching from the macro region to the variable power region in the order as described above, this movement is actually an instantaneous movement to bring about a visual sense to human eyes as if the view of angle corresponding to 80 mm is directly changed to that corresponding to 135 mm, which gives unnatural sense.
In addition, it may be considered for such a case where each of the lens groups is not stopped on the TELE side but on the WIDE side after passing through the TELE side. In this case, since the focal depth is deep on the WIDE side, if there is any scattering in the distance measuring data as described above, such a scattering is absorbed within the focal depth and cause no erroneous operation. Accordingly, although the problem of confusing the operator can be solved, the change of the angle of view sensed by the human eye is still 80 mm in the macro region--35 mm in the variable power region and, thus, the unnatural feeling is not eliminated.
The first object of the present invention is to provide an automatic focusing device for use in a camera capable of previously judging as to if the macro photographing is possible or not correctly while the variable power lens group is in the variable power region and capable of displaying an operation demand information for calling the operator's attention to appropriate procedures if it is in the possible state, thereby enabling easy and rapid operation.
The second object of the present invention is to provide an automatic focus adjusting device capable of preventing an overload from being exerted on driving means and suppressing wasteful consumption of electrical power when the focusing lens of photographing lenses is driven to the end of the driving range in the variable power region and stops there, by inhibiting the successive driving to the identical direction, capable of highly accurate focusing adjustment even if the output of the focal point detection means should vary by allowing the driving in the opposite direction and, further, capable of providing an user with appropriate information as to whether the macro photographing is possible or not in a case where the object to be focused is at a distance nearer than the nearest distance in the variable power region.
The third object of the present invention is to provide an automatic focusing device for use in a camera capable of using an automatic focusing mechanisms in common both in the variable power region and in the macro region by moving each of lens groups constituting a variable power optical system smoothly with no interference to each other upon switching operation for the region of the photographing lens from the variable power region to the macro region or, vice versa, and further unifying the direction of the focusing lens group after the switching operation.
The fourth object of the present invention is to provide a variable power optical system control device for use in a camera capable of smoothly switching without giving confusion to an operator upon switching the setting for the variable power optical system from the macro region to the variable power region with an inexpensive and simple structure and capable of eliminating the change of angle of view sensed by human eyes from a practical point of view.
The fifth object of the present invention is to provide an automatic focusing device for use in a camera capable of judging as to whether the mounted photographing lenses have the macro function or not, previously judging as to whether the macro photographing is possible or not correctly in a state where the variable power lens group is in the variable power region and if it has the macro function, displaying a demand information for calling the user's attention to appropriate procedures if it is in the possible state, thereby enabling easy and rapid operation.
The present invention provides an automatic focusing device for use in a camera using photographic lenses having a variable power region in which an entire focal length of a variable power optical system comprising a variable power lens group, a focusing lens group and a macro lens group disposed on an identical optical axis can optionally be set by the variable power lens group between a shortest focal length and a longest focal length and a macro region capable of macro photographing by the macro lens group, as well as having, as a focusing region of the focusing lens group, a variable power focusing region from an infinite position to a nearest position on the optical axis corresponding to an object distance from an infinite distance to a nearest distance and a macro focusing region capable of macro photographing in a predetermined region disposed from the nearest position on the side opposite to the infinite position, the device comprising a focal point detection means for receiving light from an object transmitting through the photographic lenses and detecting a defocusing direction and the defocusing amount for a focused position of an object relative to an intended focal point position, a region judging means for judging as to whether the variable power optical system is in the variable power region or in the macro region, a focal length detection means for outputting a focal length information corresponding to an entire system focal length when the variable power lens group is in the variable power region, a focusing drive control means for driving the focusing lens group, detecting that the focusing lens group has been driven to end of the variable power focusing region and then stopping a driving for the focusing lens group, a macro information providing means for providing a camera operator with an operation promotion information so that the variable power optical system is shifted to a macro photographing possible state when the focusing lens group is driven to end in the variable power focusing region, the defocusing directions just before the driving is stopped or just after the driving is stopped by the focusing drive control means respectively are identical with each other and the defocusing direction is directed to the nearest position and a judging indication means for calculating a macro photographing possible range to the entire system focal length set a focal length information and the defocusing amount, judging as to whether the operation promotion information should be provided or not and then indicating this to the macro information providing means.
In the automatic focusing device for use in a camera according to the present invention, it is judged as to whether an object at a distance nearer than the nearest distance can be photographed in the macro region or not properly and at a high accuracy and, if it is judged that the photographing is possible, the operation demand information calling the operator's attention to the operation of shifting to the macro region is informed. Accordingly, it is possible to avoid operator's wasteful procedures or wasteful time consumption such as he finds that focusing is impossible only after rashly shifting procedures to the macro region. In addition, there is no such disadvantage that the operator gives up photographing due to the impossible focusing in the variable power region although proper macro photographing is possible only if it is switched to the macro region, or a valuable shutter chance is lost by wastefully consuming time till he becomes aware that he only has to take the moving procedure to the macro region.
The present invention also provides an automatic focal point adjusting device including photographing lenses having a variable power region and a macro region capable of macro photographing, a focal point detection means for receiving light from an object to be focused transmitting through the photographing lenses and detecting a deviating direction of a focused position of the object relative to an intended focal point position and a focused state of the object to be focused and driving means for starting a movement of a focusing lens of the photographing lenses toward the focusing direction when a not-focused state is judged by the focal point detection means and stopping a movement when the focused state is judged, the device comprising an end detection means for detecting as to whether a driving position of the focusing lens of the photographing lenses has reached end of the driving range in the variable power region or not, an inhibition means for inhibiting an operation of the driving means when end is detected by the end detection means, a releasing means for responsing to the end detection in the end detection means, comparing data of deviating directions from the focal point detection means just before and just after detection and releasing an inhibiting operation of the inhibiting means if both of directions do not agree with each other, a region judging means for judging as to whether the photographing lenses are situated in the macro region or not and a macro information provide means for responsing to the end detection from the end detection means when it is judged that the photographing lenses are not situated in the macro region by the region judging means, comparing driving directions of the focusing lens obtained from the focal point detection means just before and just after detecting and outputting a promotion information indicating that the photographing lenses should be shifted into the macro region if both of directions agree with each other and the driving direction is toward a nearest position.
Since the automatic focal point adjusting device according to the present invention is adapted such that the operation of the driving means is inhibited instantly when the driving position for the focusing lens of the photographing lenses reaches the end of the driving range in the variable power region, it is possible to prevent overload from being exerted on the driving means and wasteful consumption of electrical power. Further, since it is so adapted that the inhibiting operation of the driving means is released and the focusing lens is driven toward the infinite position when an erroneous distance measuring information indicating that as if the object to be focused were at the distance (position) nearer than the nearest distance although it is actually at the position near the nearest distance within the focal length range in the variable power region is temporarily outputted from the focal point detection section due to the scattering in the detection output and the focusing lens is driven to and stopped at the nearest end position, focusing is made on the object to be focused situated at a position near the nearest distance. Accordingly, focusing adjustment at high accuracy is possible irrespective of the scattering in the output from the focal point detection means. Furthermore, it is also adapted so that if the object to be focused is at a position nearer than the distance corresponding to the nearest position in the variable power region, an adequate information is provided to the user as to whether the macro photographing is possible or not. Accordingly, it is possible to prevent operator's wasteful procedures or wasteful time consumption such as he finds that the focusing is impossible only after the rashly switching procedures to the macro region. It is also possible on the contrary to avoid such disadvantage that the operator gives up to take photograph because of the impossible focusing in the variable region although proper macro photographing is possible or a valuable shutter chance is lost by wastefully consuming time till he becomes awares that he has only to make switching procedures to the macro region.
The present invention also provides an automatic focusing device for use in a camera using photographic lenses having a variable power region in which an entire focal length of a variable power optical system comprising a variable power lens group, a focusing lens group and a macro lens group disposed on an identical optical axis can optionally be set by the variable power lens group between a shortest focal length and a longest focal length and a macro region capable of macro photographing by the macro lens group, as well as having, as a focusing region of the focusing lens group, a variable power focusing region from an infinite position to a nearest position on the optical axis corresponding to an object distance from the infinite distance to the nearest distance and a macro focusing region capable of macro photographing which is present substantially overlapped with the variable power focusing region, the device comprising a macro information providing means for judging as to whether a focusing in the macro focusing region is possible or not if the variable power optical system is switched to the macro region in a case where the variable power optical system is in the variable power region and a focused state can not be attained even after the fucusing lens group has reached the nearest position of the variable power focusing region and informing the result thereof to a camera operator as macro information, a variable power driving means for setting the variable power optical system to the variable power region or to the macro region and driving the variable power lens group for setting it to an optional entire system focal length in the variable power region, a focusing drive means for driving the focusing lens group, a switching actuation means capable of external operation for actuating a macro switching operation of switching the variable power optical system from the variable power region to the macro region, a switching control means for controlling the variable power driving means and the focusing driving means so that macro switching operation can be made while maintaining a predetermined relative positional relationship or a predetermined time relationship between the variable power lens group and the focusing lens group from an instance that a camera operator informed with a macro information indicating that a focusing is possible actuates the switching actuation means, a focusing lens group position detection means for detecting a position of the focusing lens group on the optical axis in the macro focusing region, a focal point detection means for receiving light from the object passing through the photographing lenses and detecting a defocusing amount of a focused position of the object relative to an intended focused position, a defocusing amount memory means for storing the defocusing amount at the instance informed with the macro information and a defocusing amount conversion means for converting the defocusing amount stored in the defocusing amount memory means into an intended focused position in the macro focusing region.
The automatic focusing device for use in a camera according to the present invention is so adapted that macro information indicating that the photographing is possible in the macro region is informed and, when an operator starts the macro switching operation based thereton, the variable power optical system is switched from the variable power region to the macro region after driving the focusing lens group to the infinite position in the variable power focusing region, as well as the defocusing amount as the distance measuring information obtained from the focal point detection means is converted by the defocusing amount conversion means into an intended focused position in the macro focusing region, which s used for the macro focusing control. Accordingly, it can be realized to unify the directionarily for the focusing and the common use of the measuring data between the variable power focusing region and the macro focusing region and, as a result, it is possible to use the focusing driving means and the focal point detection means in common for the variable power focusing control and the macro focusing control, with which the constitution of the device can be simplified by so much and the lens groups constituting the variable power optical system can be set to a predetermined relationship smoothly with no interference to each other during actuation of the macro switching operation.
The present invention also provides a variable power optical system control device for use in a camera using photographic lenses having a variable power region in which an entire focal length of a variable power optical system comprising a variable power lens group, a focusing lens group and a macro lens group disposed on an identical optical axis can optionally be set by the variable power lens group between a shortest focal length and a longest focal length and a macro region capable of macro photographing by the macro lens group, as well as having, as a focusing region of the focusing lens group, a variable power focusing region from an infinite position to a nearest position on the optical axis corresponding to an object distance from an infinite distance to a nearest distance and a macro focusing region capable of macro photographing, which is present substantially overlapped with the variable power focusing region, the device comprising a lens group driving means for setting the variable power optical system to the variable power region or to the macro region and driving the variable power lens group or the macro lens group for setting an entire system focal length in both of the regions, a region judging means for judging as to whether variable power optical system is set in the macro region or in the variable power region, a focal length detection means for outputting the focal length information corresponding to the entire system focal length when the variable power optical system is set to the variable power region, a switching actuation means capable of external operation for actuating a switching operation of switching a setting for the variable power optical system to the variable power region or to the macro region and switching control means for controlling the lens group driving means based on a focal length information when a switching operation to the variable power region is actuated by the switching actuation means in a state where the variable power optical system is set to a predetermined focal length in the macro region so that the entire system focal length in the variable power region is set substantially equal with or shorter than a predetermined focal length.
Since the variable power optical system control device according to the present invention is so adapted that the variable power optical system is set to such a focal length as substantially equal with a predetermined focal length in the macro region or to a shorter focal length in the variable power region uon switching from the macro region to the variable power region, change in the view of angle sensed by human eyes can be eliminated substantially from a practical point of view. In addition, the switching can be made smoothly with no disturbance to the operator.
The present invention further provides a display device for use in a camera using, as photographic lenses, such vari-focus lenses as having at least a variable power region in which an entire focal length of a variable power optical system comprising at least a variable power lens group and a focusing lens group disposed on an identical optical axis can optionally be set by the variable power lens group between a shortest focal length and a longest focal length, as well as having, as a focusing region of the focusing lens group, a variable power focusing region from an infinite position to a nearest position on the optical axis corresponding to an object distance from an infinite distance to a nearest distance, the device comprising a lens judging means for judging as to whether photographing lenses mounted to the camera are photographing lenses having a macro function capable of macro photographing or not, a region judging means for judging as to whether the photographing lenses are set to the macro region or not, a focal point detection means for receiving light from the object transmitting the photographing lenses, detecting a deviating direction and a focused state of the focused position relative to an intended focused position of the object and outputting them as distance measuring information and a promotion information providing means for providing a promotion information calling the camera operator's attention to that the photographing lenses are moved to the macro region when it is judged by the lens judging means that the photographing lenses have a macro function and also judged by the region judging means that the photographing lenses are not in the macro region in response to a distance measuring information indicating that the object is present at a position nearer to the nearest position.
The display device according to the present is adapted to judge whether the lenses mounted to the camera are photographing lenses having the macro function or not, judging as to whether the object at a distance nearer than the nearest distance can be photographed or not in the macro region properly and at a high accuracy if they are judged to be the photographing lenses having the macro function, and the demand information calling the operator's attention to the shifting operation to the macro region when it is judged that the photographing is possible. Accordingly, it is possible to eliminate operator's wasteful procedures or wasteful time consumption such as he finds that the focusing is impossible only after the rashly switching procedures to the macro region. It is also possible on the contrary to avoid such disadvantage that the operator gives up to take photograph because of the impossible focusing in the variable region is although proper macro photographing is possible, or a valuable shutter chance is lost by wastefully consuming time till he become aware that he has only to make switching procedures to the macro region.